The present invention relates to a method of continuously wet heat treating a long knitted or woven cloth, particularly a cylindrical one, with high temperature steam under pressure to pretreat or dye the cloth effectively.
For pretreating or dyeing a long knitted or woven cloth produced commercially, it has conventionally been done to soak the cloth with, for instance, a dye solution and to wet heat treat the resultant cloth in a steamer at a temperature lower than 100.degree. C. in batches discontinuously. In the conventional method of dyeing a cloth, therefore, no continuous treatment can be done, not only consuming a large heat energy but also causing irregularity in the degree of dyeing from batch to batch, and, moreover, since it needs a long while until the dye is fixed firmly in the cloth in wet heat treating the cloth at a temperature below 100.degree. C., such a process is obviously uneconomical.
After various studies of the present inventors over a long period for shortening the pretreating or dyeing time of a cloth, a high pressure steamer has been developed in which pretreatment or dyeing of the cloth can be done continuously in a short time of second level, and such a high pressure steamer is under practical operation. In this high pressure steamer, however, a pair of seal rolls pressed with each other is provided for supplying a cloth continuously into the steamer body while maintaining the interior of the steamer body with a wet heat under pressure, so that the cloth must be supplied in the steamer body through the seal rolls. In passing a cloth soaked with a treating solution outside of the steamer body through the seal rolls, the cloth is squeezed, causing a shortage in the amount of the treating solution in the wet heat treatment, particularly when the cloth is a cylindrical one.
Various methods and devices have been proposed by the present inventors to soak the cloth with a treating solution inside of a steamer body, but the interior of a steamer body is maintained usually with a wet heat at a temperature of about 150.degree. C. and the temperature of the treating solution to be supplied in the steamer body is at the ordinary temperature (about 20.degree. C.), having a tolerable temperature difference therebetween. In supplying a low temperature treating solution in a high temperature steamer body, the high temperature steam in the steamer body is condensed, not only lowering the humidity in the steamer body but also diluting the concentration of the treating solution being applied. Therefore, uniform treatment of a cloth, particularly a cylindrical one, can by no means be done continuously.